This proposal requests support for Elizabeth Lyons, Ph.D., M.P.H. to engage in four years of career development and mentored research activities. The goal of the LEVEL UP (Leveraging Electronic Videogames for Exercise and Leisure: Understanding Preferences of breast cancer survivors) project is for her to become an independent researcher and leader in the field of physical activity among cancer survivors. Training objectives of this award are to increase knowledge and skills related to 1) cancer survivorship, 2) physical activity and breast cancer survivorship, 3) clinical intervention trials, and 4) professional skills. Primary mentor Karen Basen-Engquist, Ph.D., is a leader in physical activity intervention research among cancer survivors. She will provide expertise in cancer survivorship, implementation of physical activity interventions among breast cancer survivors, and clinical trial development and evaluation. She will also oversee career development as a cancer control researcher. Co-mentors James Goodwin, M.D. and Abbey Berenson, M.D., Ph.D will contribute valuable expertise in breast cancer treatment and sequelae, cultural competence in cancer research, recruitment and retention in large clinical trials, and development of academic and professional skills. The proposed research project includes qualitative and quantitative formative research leading to a randomized controlled feasibility trial of a video game-based physical activity intervention. First, we will investigate exercise protocols implemented over 12 weeks in 20 breast cancer survivors. From 12 initial games, we will choose six games for inclusion in the trial, based on measured energy expenditure and enjoyment. We will create refined exercise protocols using these six games and insights from focus groups of participants. Second, we will test an intervention that uses active video games for implementation of motivating exercise and provision of behavioral tools (e.g., tracking of progress towards goals). The intervention will be compared in a 24-week randomized controlled trial (N = 60) to a control group that provides sedentary video games with an emphasis on stress relief. Participants will receive weekly brief telephone counseling over the first 12 weeks. Weeks 12 - 24 will test sustainability of activity in the absence of investigator contact. The primary outcome is objectively-measured minutes of moderate-vigorous physical activity at 12 weeks. Feasibility measurement will include attrition, self-reported acceptability, and objective measures of video game play taken from game console data. Other physiologic and psychosocial outcomes will be used to power a larger trial as part of an R01 application to be submitted in the third year of the award period. The mentored research and career development activities proposed in this application will facilitate Dr. Lyons' transition to an independent researcher and leader in cancer survivorship research.